NGC 1980 Is Not a Foreground Population of Orion: Spectroscopic Survey of Young Stars with Low Extinction in Orion A

Min Fang, Jinyoung Serena Kim, Ilaria Pascucci, Dániel Apai, Lan Zhang, Aurora Sicilia-Aguilar, Miguel Alonso-Martínez, Carlos Eiroa, Hongchi Wang

Research output: Contribution to journalArticle

12 Scopus citations

Abstract

We perform a spectroscopic survey of the foreground population in Orion A with MMT/Hectospec. We use these data, along with archival spectroscopic data and photometric data, to derive spectral types, extinction values, and masses for 691 stars. Using the Spitzer Space Telescope data, we characterize the disk properties of these sources. We identify 37 new transition disk (TD) objects, 1 globally depleted disk candidate, and 7 probable young debris disks. We discover an object with a mass of less than 0.018-0.030 M o, which harbors a flaring disk. Using the Hα emission line, we characterize the accretion activity of the sources with disks, and confirm that the fraction of accreting TDs is lower than that of optically thick disks (46% ± 7% versus 73% ± 9%, respectively). Using kinematic data from the Sloan Digital Sky Survey and APOGEE INfrared Spectroscopy of the Young Nebulous Clusters program (IN-SYNC), we confirm that the foreground population shows similar kinematics to their local molecular clouds and other young stars in the same regions. Using the isochronal ages, we find that the foreground population has a median age of around 1-2 Myr, which is similar to that of other young stars in Orion A. Therefore, our results argue against the presence of a large and old foreground cluster in front of Orion A.

Original languageEnglish (US)
Article number188
JournalAstronomical Journal
Volume153
Issue number4
DOIs
StatePublished - Apr 2017

Keywords

  • accretion, accretion disks
  • protoplanetary disks
  • stars: pre-main sequence

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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